So I accessed this loop in the past week via the road that leads into Duval Lake, north of the town of Elliot Lake. The gravel road is around 30 km long, and in good condition for about the first half. (i.e. Just about any vehicle could drive up it.) The second half gets a bit worse with bigger rocks and a bit more hilly and bushy, but most AWD or 4WD vehicles with decent clearance and good tires should be okay until the last 500 meters or so. The last 500 meters to the beach at the north end of Duval Lake is a bit iffy, but still most vehicles that have good clearance and AWD/4WD and good tires would probably be okay. I was in a Subaru with 9" clearance and was wondering if I'd make it out from the beach to the road for the week or so that I was on the loop, but it was okay getting out.
If you take this route in, you might consider parking on the road before the beach access, and portage in the 500 m or so to the beach.
I've included a file here of the GPS tracks of the portages I took. Most of the portages are marked, but some only with ribbon/not portage signs. And most of them are in passable condition with trails that can be seen. It's a portage-heavy route, and some of the portages are hilly. It's not super-easy, and I wouldn't recommend the route to someone who hasn't been on at least a few "lost canoe route" kind of routes in the past.
Here are some general comments about the portages leading out of Duval, going anti-clockwise:
Duval to first pond: Not marked with a sign. Decent portage that goes up a hill and back and forth across a small stream a few times, but you shouldn't get wet feet here in the summer. In the last 100 meters or so there's a swamp to walk/wade through just below a beaver dam... possibly might as well just put in at the beaver dam if you can, since you'll just walk through the swamp then end up on the same little pond anyway.
Pond to pond after Duval: Not marked with a sign. Uphill at start, good portage but gets kind of confusing in the middle. Another poster here had mentioned a "clear cut." It doesn't look a lot like a clear cut in 2023, but there are a few different trails in this portion, and at one point I "lost" my gear after carrying too far ahead with the canoe (was double carrying). It might be a good idea to keep your gear close so you don't end up on the wrong trail when you're on your way back to get your other stuff. There are a couple "swampy" sections to walk through, and it's kind of strange at the west end, where you have to go up some rocks to get to the pond.
Pond to "Crazy" Lake: Good portage, but it's difficult to get to since there's a swamp in the way on the east side. Portage sign is hard to see from the water.
"Crazy" Lake to Pointer Lake: Marked with a portage sign, but it's way in the distance and not possible to see from the water. Twisty and hilly portage that has a big dried-up swamp to walk over before you can actually tell you're on the portage. Fairly steep downhill at the Pointer Lake side.
Pointer Lake to West Little White River: Good portage, marked with a sign.
West Little White River to Finn Lake: Good portage, marked with sign.
Finn Lake to Town Line Lake: Marked with a sign. Up and down hills at start, then walk-along-the-side-of-a-swamp for a while. After that it's a good portage, but long.
Town Line Lake to Robb Lake: Good portage that starts on what looks like a campsite on the south end of Town Line Lake. It's just long.
Robb Lake to Kirkpatrick Lake: Here's where I had a heck of time. Others may have watched the Jonathan Kelly Video of the route where there's confusion here, and may have read other accounts. I decided to try the "snowmobile" trail out the east side of Robb Lake, but it was pretty awful. I wouldn't recommend it to anyone, but that being said, I don't REALLY know how bad the south routes through Elbow or on the 3000 m link direct from Robb to Kirkpatrick are. If someone does these sometime and has GPS of them and can comment on them, I'd love to know. Anyway, there is an actual portage sign out the east end of Robb, but whatever sadist put it there is... So it starts up a dried-up creek bed full of iffy rocks, up to the pond. Across the pond is a kind-of snow machine trail that goes up the hill, but this trail hasn't been used in years and years by snow machines. Once up the hill, the trail veers a bit right, then starts going downhill. Here is where the trail ends, and it's bush-whacking the entire way to Kirkpatrick. That portion of the portage (pond to Kirkpatrick) took me 2.5 hours, and I was cautious about losing track of my stuff as a leap-frogged canoe and gear. So it's passable, but miserable.
Kirkpatrick to Bluebird: Signed portage that is mostly passable, but gets a bit confusing about 80% of the way through when the trail leaves the woods and goes over bedrock. Then follow the left side of a dried-up-swamp for a while, then uphill at the end of the swamp (left side) to Bluebird Lake. Jonathan Kelly talks about a difficult climb on this portage- the east end is where the difficult climb is, just before Bluebird.
Bluebird to Big Horseshoe: Good portage, not signed at Bluebird end, but flagged. Good until the Big Horseshoe end, where there's a kind of mini-Diablo portage down into Big Horseshoe. I had to triple-carry here, and the boat mostly slid down the hill.
Big Horseshoe to Duval: There are a couple options here, I took the single-portage option. It wasn't signed, but obvious due to cached boats. The portage was fine, but as others have mentioned, it's a swamp on the east end and a bit difficult to load, launch, and paddle canoes for a bit until you're in the deeper water of Duval.
Hope this helps!
The file should be below, but here's a link to it in Google Drive too:
https://drive.google.com/file/d/1TLKdq_8LbgefFJJ9xxUMB5VwO8o7Irg6/view?usp=sharing